Abstract: A shut-off valve to fit the outlet end of a double faucet single spout tap in lieu of the conventional aerator screen. The valve comprises a valve body having an upstream valve seat on which is adapted to rest a disc-shape valve plug. An operant shaft extends transversely through the valve body and is provided with a handle at one end to rotate the shaft. The shaft has a central cam lapping a downstream edge portion of the valve plug. In one rotated position of the shaft, the valve plug closes the valve under the action of the upstream fluid pressure. Rotation of the shaft causes tipping of the valve plug to a fully-open position.